Internal combustion engines are coupled to fuel vapor recovery systems to allow purging of fuel vapors generated in fuel tank systems. Conventional systems control total purge flow based on an estimated purge fuel vapor concentration. This estimated purge fuel vapor concentration represents the amount of fuel vapor contained in the total purge flow from the fuel system. Fuel injection control is also adjusted based on this estimated purge concentration.
The inventor herein has recognized a disadvantage with prior art methods. In particular, the prior art methods do not show an accurate method for determining cylinder fuel vapor purge concentration. Further, the prior art does not even recognize uses of cylinder fuel vapor purge concentration. Cylinder fuel vapor purge concentration represents fuel vapor concentration in an engine cylinder, taking into account total purge flow, purge fuel vapor concentration, and cylinder fresh charge.